Lumens ,

[sestephen]

Ok, I hear that led are just as good but when retrofitting should you take the lumens in consideration? I mean if the room was designed for a lamp of 32000 lumens and you change to a 1580 lumens lamp , aren't you losing 50% of your luminance

 

[tw1156]

Efficacy and Efficiency

Efficacy and Efficiency

Welcome to the Forum,

I'm unsure of your application or original lighting source, but assuming it's non-LED and fluorescent for example let's look at the following:

Efficacy - Lumens Per Watt
Efficiency - How many lumens actually escape the fixture

LED sources - Most LED sources are tested as a complete system (efficiency is 100% typically).
Fluorescent Lamps - Lamps are given a lumen rating, but when installed in a fixture (2x4) for example, not all of those lumens are escaping.

We see crossovers of the following all the time: 32W TT (~2000 Lumens) Fluorescent Can light to a 12W LED (~1200 Lumens). The reason these match in swapping them out is because the efficiency of the 32W TT fluorescent fixture is more around 60-70%.

I hope this helps.

 

[Electric-Light]

Ok, I hear that led are just as good but when retrofitting should you take the lumens in consideration? I mean if the room was designed for a lamp of 32000 lumens and you change to a 1580 lumens lamp , aren't you losing 50% of your luminance

Perhaps you mean 15,800 lumens. Sounds like you're working with a 400W MH. Many LED sales materials are full of gimmicks even though the highest depreciating of all lamps are MH and standard grade LEDs and retrofit LEDs focused for wattage reduction often fail to provide like quality lighting. This may or may not be acceptable depending on your application. Metal halide loses 40-50% of new output, and common LEDs lose 30% over lifetime.

Not all MH fixtures are the same. Many intentionally use a large, heavy, textured glass bell jar that "glows" all the way around instead of a much lighter and cheaper polished aluminum for better lighting quality even though the latter provides more FC on desk. Many of those LED drop-ins look like a shower head for whales with visible LED pellets. This casts multi-edged shadows without a whole lot of light spilling out to the sides creating a very gas stationy feel. This illumination gain is comparable to replacing a regular high mounted light bulb with a PAR bulb of the same wattage.

At a gas station, anything out the side is lost. Inside a room is quite different. Whats your application?